Optical coherence tomography (OCT) is an emerging optical imaging technique that enables micron-scale, cross-sectional, and three-dimensional (3D) imaging of biological tissues in situ and in real-time. OCT functions as a type of “optical biopsy,” imaging tissue microstructure with resolutions approaching that of standard histopathology, but without the need to remove and process tissue specimens. Accordingly, OCT captures and digitizes visual images of tangible objects such as biological tissue. The penetration depth of OCT is usually 1-2 mm in biological tissues. OCT has been used for a wide range of clinical and biomedical applications particularly in humans and animals, including ophthalmology, cardiovascular imaging, endoscopy imaging, cancer imaging, dental applications, and research imaging applications.
Current commercial ophthalmic OCT systems operate at 20-70 kHz. Each 3D scan covering 512×512 A-lines takes 3-10 seconds. Commercial cardiovascular and endoscopic OCT imaging systems operate at 100 kHz-200 kHz A-line rate in order to cover a large imaging field. Higher imaging speed at over 1 MHz A-line rate as a goal is ultimately desirable for faster imaging and less motion artifacts. However, currently there is no commercially-available wavelength tunable laser or high speed line-scan camera that operates at that speed. Imaging speeds for OCT, characterized as number of A-scans per second, is limited by the line rate of line-scan cameras for spectral-domain OCT (SD-OCT) or by the laser sweep rate for swept-source OCT (SS-OCT).